In conventional wire-cut electrical discharge machining, when thin sheet-shaped wafers are made by cutting a columnar workpiece, many wires are used to perform simultaneous cutting. In order to increase productivity of the above cutting operation, a method is proposed in which one piece of wire is repeatedly engaged between a plurality of guide rollers. A wire-cut electrical discharge machining apparatus using this method is such that cutting wire portions are formed where a wire is disposed in parallel at fixed intervals, and by causing the cutting wire portions to come close to the workpiece and also using power feed contacts to separately feed power to each of the cutting wire portions, discharges are created simultaneously between each cutting wire portion and the workpiece, to perform cutting in parallel at a plurality of places (refer to Patent Document 1, for example).
Further, it is known that a wire-cut electrical discharge machining apparatus where one piece of wire is repeatedly engaged between each of a plurality of guide rollers, is equipped with a press rod that suppresses vibrations of power feed contacts and a cutting wire portion (refer to Patent Document 2, for example). Moreover, it is known that the wire vibration can also be suppressed by pressing the wire for wire-cut electrical discharge machining against the power feed contacts (refer to Patent Document 3, for example).
In addition, Patent Document 4 describes guide rollers formed with grooves, and power feed contacts that feed power to a plurality of wires, for a wire-cut machining apparatus.